Specifications

HARDWARE PREPARATION AND INSTALLATION
2-4 MPC505EVBUM/D
Table 2-2. MPFB Jumper Header Descriptions (continued)
Jumper
Header Type Description
J4
Keep alive
power 1 select
header
3 2 1
Jumper installed on pins 1 and 2 (factory default); MCU-internal oscillator,
time base, and decrementer operates as long as power is applied to the
EVB (+3.3 Vdc present on the VKAPWR2 pin of the MCU).
+3.3 Vdc external power supply attached to jumper header J4 pins 2 and 3;
maintains MCU-internal oscillator, time base, and decrementer operates
after EVB power is turned OFF.
J5 Unused
J6,
System clock
selection
header
3
2
1
Jumper installed on pins 1 and 2 (factory default); jumper headers J6 and
J7 select the MCU clock mode. The state of this signal during reset selects
the source of the system clock.
J7
System clock
selection
header
3
2
1
Jumper installed on pins 1 and 2 (factory default); jumper headers J6 and
J7 select the MCU clock mode.
HARDWARE PREPARATION AND INSTALLATION
MPC505EVBUM/D 2-5
2.2.1 Crystal Clock Select Header (J1)
Jumper header J1 connects the crystal clock to the MCU XTAL pin clock source. The drawing
below shows the factory configuration: bus wire soldered on pins 1 and 2. This configuration
selects the crystal clock source; crystal in socket at located Y1. When you want to use the clock
oscillator as the EVB clock, remove the bus wire on J1 and move the bus wire on J2 from pins 2
and 3 to pins 1 and 2 (see paragraph 2.2.2). This disconnects the MCU XTAL pin from the
crystal clock circuit at location Y1 and selects the clock oscillator (U7) as the MCU clock source.
The frequency of the crystal clock circuit is 4 MHz. The frequency of the crystal oscillator circuit
can be as fast as 40 MHz.
J1
21
Bus Wire
The EVB comes with a 4 MHz crystal and a socket for a crystal oscillator. The EVB is factory
configured to use the 4 MHz crystal as the input. You can configure the clock frequency up to 33
MHz by setting the MF bits (bits 9-12) and RFD bits (bits 28-31) in register SCCR at address
0x8007_FC50 (shown in Table 2-3).
Table 2-3. MF and RFD Bits Required to Set Clock Speed
CLKOUT (megahertz)
RFD [0:3] MF=
X000
(X4)
MF=
X001
(X5)
MF=
X010
(X6)
MF=
X011
(X7)
MF=
X100
(X8)
MF=
X101
(X9)
MF=
X110
(X10)
MF=
X111
(X11)
0 = 0000 16 20 24 28 32 NA NA NA
1 = 0001 8 10 12 14 16 18 20 22
2 = 0010 4567891011
3 = 0011 2 2.5 3
2
3.5 4 4.5 5 5.5
4 = 0100 1 1.25 1.5 1.75 2 2.25 2.5 2.75
5 = 0101 .5 .625 .75 .875 1 1.125 1.25 1.375
6 = 0110 .25 .313 .375 .438 .5 .563 .625 .688
7 = 0111 .125 .156 .188 .219 .25 .281 .313 .344
Fr
eescale S
emiconduct
or
, I
Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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